Calculate linear footage, square yards, Waterfall vs Hollywood French-cap installation yardage, heavy-traffic cushion padding, and tack strip requirements.
Avoid running short on the last riser, ordering excess yardage, or buying unsafe spongy padding.
Carpenters and DIYers often calculate stair length as simple diagonal hypotenuse or tread depth alone, forgetting that each step requires covering the vertical riser and bullnose curvature, leaving them short right at the bottom floor.
The tailored Hollywood (French Cap) method tucks carpet tightly beneath the bullnose lip, consuming an extra 1.0 to 1.5 inches per riser. Over 15 steps, this consumes up to two extra linear feet that standard diagonal estimates miss.
Standard soft 1/2-inch bedroom padding collapses rapidly on stair edges under concentrated heel impact, pulling tack strips loose. CRI standards mandate high-density 7/16" 8-lb foam or felt underlayment for lasting safety.
Carpet mills quote pricing per square yard (9 sq ft), while lumber and runners are sold by linear feet or inches. Our dynamic formula handles conversions automatically, preventing expensive ordering unit errors.
Five straightforward steps to calculate exact stair carpet and runner material.
Count every vertical riser from the ground floor up to and including the top landing riser.
Measure horizontal tread depth, vertical riser height, and the rounded front nosing curve.
Select Waterfall (straight cascade) or Hollywood French Cap (stapled snugly under the nosing).
Choose runner widths (27", 30", 32") or wall-to-wall dimensions (36"+) and add landing platforms if needed.
Review total linear feet, square yards, padding, tack strips, and estimated material budget.
Designed for flooring contractors, carpet installers, interior remodelers, and DIY homeowners.
Precisely factors in the additional contouring footage required when stapling carpet beneath nosing lips in the French Cap method compared to modern waterfall cascading.
Calculates required architectural tack strips (two strips per step mounted 1/2" off the crotch corner) to guarantee secure carpet anchoring under heavy tension.
Seamlessly incorporates mid-flight landings, L-shaped switchbacks, and top platforms into single roll takeoffs without separate manual area calculations.
Renders an interactive step profile illustrating tread depths, riser heights, and the visual differences in how carpet hugs or drapes over stair bullnosing.
Carpet and Rug Institute (CRI 105) residential carpet installation standards.
| Feature / Metric | Waterfall Installation | Hollywood (French Cap) | Upholstered Bullnose |
|---|---|---|---|
| Visual Appearance | Clean, modern, continuous drape | Tailored, architectural, defined lip | Full wrap around open tread ends |
| Extra Carpet / Step | Baseline (0" extra) | +1.0" to +1.5" per step | +2.0" to +3.0" per step |
| Best Carpet Styles | Heavy Berbers, thick plush, loop pile | Low-profile cut pile, patterned runners | Fine woven wool, dense velvets |
| Labor Complexity | Fast & straightforward (DIY friendly) | Intermediate (staple gun under lip) | Advanced (spindle notches & cuts) |
| Recommended Cushion | 7/16" 8-lb density bonded foam | 3/8" or 7/16" 8-lb rubber or felt | 3/8" synthetic fiber pad |
Essential stair carpeting measurements, cushion standards, and yardage estimation guidance.
